A variety of nodes including a Web server, an application server and a DB (DataBase) server are set up in a data center where each of these nodes is usually made redundant to be prepared for an accident or a failure.
There is known a redundancy technique, for example, in which a primary node and a secondary node are provided as nodes in the data center so that, when the primary node fails, the secondary node instead takes over processing of the failed primary node and continues the processing.
There is also known a technique in which a secondary data center provided as a backup of a primary data center takes over processing executed in the primary data center and continues the processing, when the primary data center is damaged.
Patent Literature 1: Japanese Laid-open Patent Publication No. 2008-134986
When a failure occurs in a node transferring a log from the primary data center to the secondary data center, the log is not transferred to the secondary data center until the node is restored. Accordingly, it may be adapted to further provide a path through which update information of data is transferred from the secondary node in the primary data center to the secondary data center. There is a possibility, however, that the switching of the path through which the update information is transferred causes an increase in a running cost as well as complication of switchover processing caused by setting a new path, the switching being forced in response to the operation of a substitute node.